BrainMap

Raluca Florentina Negrea

Dr.

Researcher - INSTITUTUL NATIONAL DE CERCETARE - DEZVOLTARE PENTRU FIZICA MATERIALELOR BUCURESTI RA

Researcher

Curriculum Vitae (21/09/2017)

Expertise & keywords

Atomically resolved structure and interface related phenomena in nano-scale modulated smart materials Call name: Exploratory Research Projects - PCE-2012 call
PN-II-ID-PCE-2012-4-0362 2013 - 2016

Role in this project:

Coordinating institution: INSTITUTUL NATIONAL DE CERCETARE - DEZVOLTARE PENTRU FIZICA MATERIALELOR BUCURESTI RA

Project partners: INSTITUTUL NATIONAL DE CERCETARE - DEZVOLTARE PENTRU FIZICA MATERIALELOR BUCURESTI RA (RO)

Affiliation: INSTITUTUL NATIONAL DE CERCETARE - DEZVOLTARE PENTRU FIZICA MATERIALELOR BUCURESTI RA (RO)

Project website: http://www.infim.ro/projects/atomically-resolved-structure-and-interface-related-phenomena-nano-scale-modulated-smart

Abstract:

Physical properties of advanced materials like artificial multiferroics, multilayered structures of semiconductors, shape memory alloys (SMA) result from the interaction between the micro- or nano-scale components (crystal grains, thin films), involving interface processes. The importance of the interface phenomena and of the associated structural defects increases with the size reduction of the involved crystal grains or thin layers. Getting accurate structural information at and near the interface between the nanoscaled components (atomic structure of the interface, associated extended defects, strain fields) becomes mandatory in understanding and designing the physical properties of new materials. Advanced techniques of analytical electron microscopy along with consecrated structural and thermal analysis techniques using state-of-the-art equipments will be mainly employed for thorough microstructural investigations on two classes of materials for which interface phenomena play a crucial role: i. artificial multiferroics and ii. shape memory alloys.

The project specific objectives are:

1. Atomic structure of interfaces and structural defects in artificial multiferroics.

2. Strain field and composition mapping at atomic scale around interfaces and structural defects in artificial multiferroics.

3. Correlation between structural phase transitions and strain fields in nanoscale modulated SMAs.

4. Atomically resolved crystal structure in nanoscale modulated SMAs.

Effect of interfaces on charge transport in ferroic/multiferroic heterostructures Call name: Complex Exploratory Research Projects - PCCE-2011 call
PN-II-ID-PCCE-2011-2-0006 2012 - 2016

Role in this project:

Coordinating institution: National Institute of Materials Physics

Project partners: National Institute of Materials Physics (RO); National Institute of Materials Physics (RO); National Institute of Materials Physics (RO); National Institute of Materials Physics (RO); National Institute of Materials Physics (RO); Alexandru Ioan Cuza University (RO)

Affiliation: National Institute of Materials Physics (RO)

Project website: http://www.infim.ro/projects/effect-interfaces-charge-transport-ferroelectricmultiferroic-heterostructures

Abstract:

The main objective of the project is to perform a detailed study of interfaces and their effect on the charge transport properties in a number of well defined artificial multiferroic structures. Charge transport is beneficial in some cases, for example in tunnel junctions, but can be detrimental in other cases, as for example devices based on magnetoelectric effect or in capacitor like structures. In all cases, at least the interfaces with the metallic electrodes are involved in charge transport, but other interfaces can be also involved if multilayer structures are used. The study will be performed on thin films and/or nanostructures, therefore a significant influence of interfaces on the electronic and ionic charge transport is expected. The start will be from simple capacitor-like structures, to elucidate the problem of electrode interfaces in the case of various ferroic oxides. Further on charge transport in relation with interfaces will be studied in mode complex, multilayer structures with possible applications in tunel junctions, diodes or field effect devices.

The project involves 6 research teams from 2 host institutions, one of which is the National Institute of Materials Physics from Bucharest-Magurele, and the other one is the Alexandru Ioan Cuza University (UAIC) from Iassy. The composition of the teams is a mixes experienced researchers with excellent track records regarding preparation, characterization and modelling of advanced multifunctional materials including oxides, and young scientists at the beginning of their carriers. Some 12 PhD thesis are expected to start during the project. The project is expected to have a major impact not only at the basic science level, reflected by publications in high ranking journals, but also at the level of applied research, as for example manipulation of charge transport through designing specific interfaces or developement of new oxide architectures for ferroelectric field effect controlled of spin currents.

INFRARED-PUMPED UPCONVERSION GLASS-CERAMIC NANORODS FOR PHOTONICS APPLICATIONS Call name: Exploratory Research Projects - PCE-2011 call
PN-II-ID-PCE-2011-3-0403 2011 - 2016

Role in this project:

Coordinating institution: Institutul National de Fizica Materialelor

Project partners: Institutul National de Fizica Materialelor (RO)

Affiliation: Institutul National de Fizica Materialelor (RO)

Project website: http://www.infim.ro/projects/infrared-pumped-upconversion-glass-ceramic-nanorods-photonics-applications

Abstract:

In the present project we intend to use glass-ceramic technology in order to obtain obtain rare-earths doped LiYF4 glass-ceramics nanorods and to investigate their optical and up-conversion properties. Glass ceramics technology is based on a controlled crystallization of a low phonon energy nanocrystalline phase embedded among the glassy matrix. The material remains transparent because light scattering is avoided due to nano-scale size of the precipitated crystals.

The idea of the project is to combine the advantages of the sol-gel glass method (simplicity, ability to control the purity and homogeneity of the final materials on a molecular level,) with the waveguiding properties of the nanorods.

LiYF4 glass-ceramics nanorods will be prepared by using the template method and nanoporous polycarbonate membranes; RE-doped nanorods will “grow” from the gel by using capillarity forces. After drying followed by thermal annealing at relatively high temperatures RE-doped fluoride nanocrystals (YLiF4) precipitate inside the amorphous glass-ceramic nanorods showing enhanced luminescence and up-conversion properties

The research efforts will be concentrated on luminescence and up-conversion effects after doping with (Eu3+, Er3+-Yb3+ and Ho3+) and the way how are influenced by the preparative conditions as nanorods size, dopant concentration, nanocrystalline fraction.

Microstructural transformations of thin films by pulsed laser irradiation at fluences lower than the ablation threshold Call name: Exploratory Research Projects - PCE-2011 call
PN-II-ID-PCE-2011-3-0268 2011 - 2016

Role in this project:

Coordinating institution: Institutul National de Cercetare Dezvoltare pentru Fizica Materialelor

Project partners: Institutul National de Cercetare Dezvoltare pentru Fizica Materialelor (RO)

Affiliation: Institutul National de Cercetare Dezvoltare pentru Fizica Materialelor (RO)

Project website: http://www.infim.ro/projects/microstructural-transformations-thin-films-pulsed-laser-irradiation-fluences-lower-ablation

Abstract:

The project refers to the microstructural transformations induced on thin films by pulsed laser irradiation at low fluences, lower than the ablation threshold. At microscopic scale, the laser irradiation actions shows some new features which are related to the laser wavelength, especially in the case of coherent laser radiation. The project work is focused on the photomechanical effect of the coherent laser beam on the structure of densified amorphous sol-gel oxide films, on structural phase modifications in mixed thin films and on the behavior of the melted metallic films and microsphere formation under the action of high power laser pulses.The structural studies are performed by conventional and high resolution transmission electron microscopy (TEM), atomic force microscopy (AFM), electron and X ray diffraction.

Eco-friendly design/synthesis of nanooxides: control of size, shape, morphology and fuctionalization of ZnO by polysaccharide-assisted methodologies Call name: Exploratory Research Projects - PCE-2011 call
PN-II-ID-PCE-2011-3-0473 2011 - 2016

Role in this project: Partner team leader

Coordinating institution: Institutul de Chimie Fizica "Ilie Murgulescu" al Academiei Romane

Project partners: Institutul de Chimie Fizica "Ilie Murgulescu" al Academiei Romane (RO)

Affiliation: Institutul de Chimie Fizica "Ilie Murgulescu" al Academiei Romane (RO)

Project website: http://www.icf.ro/pr_2011/polysaccharides.ppt

Abstract:

The present project has as general scientific objective the developing of innovative green strategies polysaccharides-assisted for the design/synthesis of tailor made oxide-based nanomaterials, exploiting polysaccharides diverse and versatile properties (water-solubility, polyfunctionality, hydrophilicity, chemical reactivity, chirality, chelation/coordination, gelling, assembling and adsorption abilities). Precipitation, combustion, hydrothermal, forced hydrolysis and gel-templates methodologies will be elaborated in order to tune the size, morphology, structure and functionalization of the oxides materials. In these protocols, polysaccharides will be conditioned to act as: (i) stabilizers, (ii) templates (hard and soft), (iii) surface functionalizing agents and, (iv) carbon source. The developed synthetic approaches will use polysaccharides build up from D-glucose units linked by α- (starch, dextran) and β-glycosidic bonds (methyl-cellulose), with distinct polymerization degree, chain branching and rheological properties. ZnO, as well as ZnO/C and ZnO-polysaccharides composites of nanomeric sizes (50-300 Å) and various morphologies (including hierarchical and spherical structures as sphere, core/shell, hollow sphere, jingle-bell) and functionalizations are intended to be obtained. The assessment of a relationship with large degree of generalization between polysaccharide-synthesis-oxide represents benefits either from fundamental and applicative research points of view.

FILE DESCRIPTION	DOCUMENT
List of research grants as project coordinator or partner team leader
Significant R&D projects for enterprises, as project manager
R&D activities in enterprises
Peer-review activity for international programs/projects